diff --git a/src/vs/workbench/api/common/extHostComments.ts b/src/vs/workbench/api/common/extHostComments.ts
index 5411bbc9f77..de6aa82e298 100644
--- a/src/vs/workbench/api/common/extHostComments.ts
+++ b/src/vs/workbench/api/common/extHostComments.ts
@@ -451,6 +451,10 @@ export class ExtHostCommentThread implements vscode.CommentThread {
 	readonly handle = ExtHostCommentThread._handlePool++;
 	public commentHandle: number = 0;
 
+	set threadId(id: string) {
+		this._id = id;
+	}
+
 	get threadId(): string {
 		return this._id!;
 	}